The Organization of the Petroleum Exporting Countries, or OPEC, describes itself as "a permanent intergovernmental organization of 12 oil-exporting developing nations that coordinates and unifies the petroleum policies of its Member Countries."
Historically, the organization has exerted considerable influence on the world oil market, with many even characterizing it as a cartel. Over the past three decades or so, it has produced a little less than half of the world's oil, with its Gulf State members still controlling most of the world's crude oil spare capacity. By lowering their collective output, OPEC members can push global oil prices higher, or so the logic goes...............................................Full Article: Source